d4-golang-utils/config/config.go

106 lines
2.4 KiB
Go

package config
import (
"bytes"
"fmt"
"io"
"log"
"net"
"os"
"regexp"
"strings"
)
// IsNet checks whether the string host is a valid
// IPv6 or IPv4 address
func IsNet(host string) (bool, string) {
// DNS regex
validDNS := regexp.MustCompile(`^(([a-zA-Z]{1})|([a-zA-Z]{1}[a-zA-Z]{1})|([a-zA-Z]{1}[0-9]{1})|([0-9]{1}[a-zA-Z]{1})|([a-zA-Z0-9][a-zA-Z0-9-_]{1,61}[a-zA-Z0-9]))\.([a-zA-Z]{2,6}|[a-zA-Z0-9-]{2,30}\.[a-zA-Z
]{2,3})$`)
// Check ipv6
if strings.HasPrefix(host, "[") {
// Parse an IP-Literal in RFC 3986 and RFC 6874.
// E.g., "[fe80::1]:80".
i := strings.LastIndex(host, "]")
if i < 0 {
log.Println("Unmatched [ in destination config")
return false, ""
}
if !validPort(host[i+1:]) {
log.Println("No valid port specified")
return false, ""
}
// trim brackets
if net.ParseIP(strings.Trim(host[:i+1], "[]")) != nil {
return true, host
}
} else {
// Ipv4 or DNS name
ss := strings.Split(host, ":")
if len(ss) > 1 {
if !validPort(":" + ss[1]) {
log.Println("No valid port specified")
return false, ""
}
// if not nil, its a valid IP adress
if net.ParseIP(ss[0]) != nil {
return true, host
}
// if "localhost", its valid
if strings.Compare("localhost", ss[0]) == 0 {
return true, host
}
// check against the regex
if validDNS.MatchString(ss[0]) {
return true, host
} else {
log.Println(fmt.Sprintf("DNS/IP: %s, Server Port: %s", ss[0], ss[1]))
return false, ""
}
}
}
return false, host
}
// validPort reports whether port is either an empty string
// or matches /^:\d*$/
func validPort(port string) bool {
if port == "" {
return false
}
if port[0] != ':' {
return false
}
for _, b := range port[1:] {
if b < '0' || b > '9' {
return false
}
}
return true
}
// ReadConfigFile takes two argument: folder and fileName.
// It reads its content, trims\n and \r, and return []byte
// All errors are Fatal.
func ReadConfigFile(folder string, fileName string) []byte {
f, err := os.OpenFile("./"+folder+"/"+fileName, os.O_RDWR|os.O_CREATE, 0666)
defer f.Close()
if err != nil {
log.Fatal(err)
}
data := make([]byte, 100)
count, err := f.Read(data)
if err != nil {
if err != io.EOF {
log.Fatal(err)
}
}
if err := f.Close(); err != nil {
log.Fatal(err)
}
// trim \r and \n if present
r := bytes.TrimSuffix(data[:count], []byte("\n"))
return bytes.TrimSuffix(r, []byte("\r"))
}